Commercial use products are generally designed to have a substantial shelf life. The products need to be manufactured at one site, transported possibly over a considerable distance to a depot or other storage facility prior to further transport to a point of sale. The product may then spend considerable time on a retailer's shelf prior to purchase and further storage by the user whether for individual use or use in, for example, a workplace, institution or the like. Storage typically takes place under uncontrolled conditions including considerable variation in temperature.
In order to keep bacterial and fungal growth in such products at an acceptable level it is conventional practice for the products to contain a preservative. Many preservatives are available. The appropriate preservative has to be selected with regard to its efficacy and its acceptability in the product.